This research will examine cross-sectional and prospective predictors of adolescent obesity using a social-ecological framework. We will recruit 420 youth and one of their parents from an existing cohort of youth who are currently participating in the Minnesota Adolescent Community Cohort (MACC) study. The MACC cohort is a representative sample, drawn from 60 geopolitical units throughout the state of Minnesota, and has been followed for 4 years as part of a study examining the effects of state and local tobacco programs on youth tobacco use. Dr. Jean Forster is the Principal Investigator for this on-going study. For our TREC research, we will invite students in the MACC cohort who are 15-16 years old and live in the metro area of Minneapolis and St. Paul to be involved in this study of the etiologic factors of obesity in adolescents. We will assess potential obesogenic factors at the individual, family, school and community level by collecting data at three time points over a period of 24 months. Individual measures will include anthropometry and a variety of psychosocial, preference and behavioral assessments related to eating and activity. Family measures will include family socioeconomic status, parent weight and body composition, family meal and activity patterns, and the home food and activity environments. School level measures will include opportunities for physical activity, competitive foods, and school food and activity policies. Community-level measures will include the use of Geographical Information System (CIS) to assess obesogenic environmental factors such as the presence of walking and bike paths, convenience stores, and fast food restaurants. This research is multidisciplinary involving researchers from across four departments at the University of Minnesota (the Division of Epidemiology, School of Nursing, School of Kinesiology, and the College of Architecture and Landscape Architecture) and including scientists with a expertise in the biological sciences, exercise physiology, nutrition, the behavioral sciences, psychology, and urban planning. This research proposal is intended to be the first in a series of proposals that will include following the cohort into young adulthood to assess obesity risk and related cancers, help in directing the focus of future interventions to prevent the onset of childhood overweight and obesity in order to reduce chronic disease risk.